Chemical name of solifenacin is (1S)-1-phenyl-1,2,3,4-tetrahydroisoquinoline-2-carboxylic acid (3R)-quinuclidin-3-yl ester, and it has the following chemical structure.

Solifenacin or a salt thereof is a compound known as a muscarine M3 receptor antagonist (Patent Reference 1, Non-patent Reference 1, Non-patent Reference 2, Non-patent Reference 3) and is on the market as a therapeutic agent for pollakiuria and urinary incontinence accompanied by overactive bladder. In addition, its usefulness for interstitial cystitis (Patent Reference 2), tension alleviation of ciliary muscle (Patent Reference 3), irritable bowel syndrome (Non-patent Reference 4) and the like has also been reported.
Regarding solifenacin or a salt thereof, the following production method X and production method Y are specifically known (Patent Reference 1).
(a) Production Method X
(b) Production Method Y

In addition, the following production method is known as a method for producing compounds having similar structures, but there is no case in which this production method was applied to the production of solifenacin (Patent Reference 4).
(c) Production Method Z
[In the formulae, Alk represents methyl or ethyl.]    Patent Reference 1: International Publication WO 96/20194    Patent Reference 2: International Publication WO 2003/6019    Patent Reference 3: JP-A-2002-104968    Patent Reference 4: JP-A-2003-267977    Non-patent Reference 1: Current Opinion in Central & Peripheral Nervous System Investigational Drugs, 2000, vol. 2, no. 3, pp. 321-325    Non-patent Reference 2: Drugs of the Future, 1999, vol. 24, no. 8, pp. 871-874    Non-patent Reference 3: Naunyn-Schmiedeberg's Archives of Pharmacology, 2002, vol. 366, no. 2, pp. 97-103    Non-patent Reference 4: Japanese Journal of Pharmacology, 2001, vol. 86, no. 3, pp. 281-288